Effects Of Dietary Calcium Deprivation On Urinary Calcium Excretion Rates In Laboratory Rabbits

A metabolic balance study was used to investigate the renal adaptation to dietary calcium deprivation in laboratory rabbits. This was accomplished by first feeding the rabbits a +Ca (0.9% Ca) diet to establish pre-deprivation urinary calcium excretion rates (UVq3) and urinary phosphorus excretion rates (UVp), which may be referred to as baseline values. The rabbits were then fed a calcium deficient diet (0.08% Ca) and later were re-fed the +Ca diet. Daily measurements of food and water intake as well as fecal and urinary output were made during the entire study. The urine which was collected daily was analyzed for calcium and phosphorus content, and daily urinary excretion rates of both were calculated for each rabbit. The dietary calcium deprivation diminished urinary Ca excretion within hours in the laboratory rabbit and sustained deprivation resulted in complete elimination of Ca from the urine in approximately two weeks. Re-feeding the calcium-deprived rabbits a +Ca diet resulted in the immediate appearance of Ca in the urine, but the UVq3 were persistently below pre-deprivation values. Furthermore, we have shown that pre-deprivation UVca values can be achieved and maintained or exceeded upon the re-feeding of the +Ca diet following sustained dietary calcium deprivation

In utero DDT and DDE exposure and obesity status of 7-year-old Mexican-American children in the CHAMACOS cohort.

BackgroundIn utero exposure to endocrine disrupting compounds including dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) has been hypothesized to increase risk of obesity later in life.ObjectivesThe Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study is a longitudinal birth cohort of low-income Latinas living in a California agricultural community. We examined the relation of in utero DDT and DDE exposure to child obesity at 7 years of age. We also examined the trend with age (2, 3.5, 5, and 7 years) in the exposure-obesity relation.MethodsWe included 270 children with o,p´-DDT, p,p´-DDT, and p,p´-DDE concentrations measured in maternal serum during pregnancy (nanograms per gram lipid) and complete 7-year follow-up data including weight (kilograms) and height (centimeters). Body mass index (BMI; kilograms per meter squared) was calculated and obesity was defined as ≥ 95th percentile on the sex-specific BMI-for-age Centers for Disease Control and Prevention 2000 growth charts.ResultsAt 7 years, 96 (35.6%) children were obese. A 10-fold increase in o,p´-DDT, p,p´-DDT, or p,p´-DDE, was nonsignificantly associated with increased odds (OR) of obesity [o,p´-DDT adjusted (adj-) OR = 1.17, 95% CI: 0.75, 1.82; p,p´-DDT adj-OR = 1.19, 95% CI: 0.81, 1.74; p,p´-DDE adj-OR = 1.22, 95% CI: 0.72, 2.06]. With increasing age at follow-up, we observed a significant trend toward a positive association between DDT and DDE exposure and odds of obesity.ConclusionWe did not find a significant positive relation between in utero DDT and DDE exposure and obesity status of 7-year-old children. However, given the observed trend with age, continued follow-up will be informative

Levels and Determinants of DDT and DDE Exposure in the VHEMBE Cohort.

BackgroundAlthough indoor residual spraying (IRS) is an effective tool for malaria control, its use contributes to high insecticide exposure in sprayed communities and raises concerns about possible unintended health effects.ObjectiveThe Venda Health Examination of Mothers, Babies and their Environment (VHEMBE) is a birth cohort study initiated in 2012 to characterize prenatal exposure to IRS insecticides and exposures' impacts on child health and development in rural South Africa.MethodsIn this report, we describe the VHEMBE cohort and dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) serum concentrations measured in VHEMBE mothers when they presented for delivery. In addition, we applied a causal inference framework to estimate the potential reduction in population-level p,p'-DDT and p,p'-DDE serum concentrations under five hypothetical interventions. A total of 751 mothers were enrolled.ResultsSerum concentrations of p,p' isomers of DDT and DDE were above the limit of detection (LOD) in ≥98% of the samples, whereas the o,p' isomers were above the LOD in at least 80% of the samples. Median (interquartile range) p,p'-DDT and p,p'-DDE serum concentrations for VHEMBE cohort participants were 55.3 (19.0-259.3) and 242.2 (91.8-878.7) ng/g-lipid, respectively. Mothers reporting to have lived in a home sprayed with DDT for malaria control had ~5-7 times higher p,p'-DDT and p,p'-DDE serum concentrations than those who never lived in a home sprayed with DDT. Of the five potential interventions tested, we found increasing access to water significantly reduced p,p'-DDT exposure and increasing the frequency of household wet mopping significantly reduced p,p'-DDT and p,p'-DDE exposure.ConclusionOur findings suggest that several intervention approaches may reduce DDT/DDE exposure in pregnant women living in IRS communities. https://doi.org/10.1289/EHP353